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lib/alsa/HwSetup: return effective parameters

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This commit is contained in:
Max Kellermann 2017-10-26 12:13:00 +02:00
parent b7e035b6f3
commit e2a74051dc
3 changed files with 45 additions and 33 deletions
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27
src/lib/alsa/HwSetup.cxx
View File

@ -176,11 +176,14 @@ SetupSampleFormat(snd_pcm_t *pcm, snd_pcm_hw_params_t *hwparams,
return err;
}
void
SetupHw(snd_pcm_t *pcm, snd_pcm_hw_params_t *hwparams,
HwResult
SetupHw(snd_pcm_t *pcm,
unsigned buffer_time, unsigned period_time,
AudioFormat &audio_format, PcmExport::Params &params)
{
snd_pcm_hw_params_t *hwparams;
snd_pcm_hw_params_alloca(&hwparams);
int err;
unsigned int period_time_ro = period_time;
@ -285,6 +288,26 @@ SetupHw(snd_pcm_t *pcm, snd_pcm_hw_params_t *hwparams,
if (err < 0)
throw FormatRuntimeError("snd_pcm_hw_params() failed: %s",
snd_strerror(-err));
HwResult result;
err = snd_pcm_hw_params_get_format(hwparams, &result.format);
if (err < 0)
throw FormatRuntimeError("snd_pcm_hw_params_get_format() failed: %s",
snd_strerror(-err));
err = snd_pcm_hw_params_get_buffer_size(hwparams, &result.buffer_size);
if (err < 0)
throw FormatRuntimeError("snd_pcm_hw_params_get_buffer_size() failed: %s",
snd_strerror(-err));
err = snd_pcm_hw_params_get_period_size(hwparams, &result.period_size,
nullptr);
if (err < 0)
throw FormatRuntimeError("snd_pcm_hw_params_get_period_size() failed: %s",
snd_strerror(-err));
return result;
}
} // namespace Alsa

9
src/lib/alsa/HwSetup.hxx
View File

@ -29,6 +29,11 @@ struct AudioFormat;
namespace Alsa {
struct HwResult {
snd_pcm_format_t format;
snd_pcm_uframes_t buffer_size, period_size;
};
/**
* Wrapper for snd_pcm_hw_params().
*
@ -38,8 +43,8 @@ namespace Alsa {
* by this function
* @param params to be modified by this function
*/
void
SetupHw(snd_pcm_t *pcm, snd_pcm_hw_params_t *hwparams,
HwResult
SetupHw(snd_pcm_t *pcm,
unsigned buffer_time, unsigned period_time,
AudioFormat &audio_format, PcmExport::Params &params);

42
src/output/plugins/AlsaOutputPlugin.cxx
View File

@ -392,38 +392,22 @@ inline void
AlsaOutput::Setup(AudioFormat &audio_format,
PcmExport::Params &params)
{
snd_pcm_hw_params_t *hwparams;
snd_pcm_hw_params_alloca(&hwparams);
const auto hw_result = Alsa::SetupHw(pcm,
buffer_time, period_time,
audio_format, params);
Alsa::SetupHw(pcm, hwparams,
buffer_time, period_time,
audio_format, params);
snd_pcm_format_t format;
if (snd_pcm_hw_params_get_format(hwparams, &format) == 0)
FormatDebug(alsa_output_domain,
"format=%s (%s)", snd_pcm_format_name(format),
snd_pcm_format_description(format));
snd_pcm_uframes_t alsa_buffer_size;
int err = snd_pcm_hw_params_get_buffer_size(hwparams, &alsa_buffer_size);
if (err < 0)
throw FormatRuntimeError("snd_pcm_hw_params_get_buffer_size() failed: %s",
snd_strerror(-err));
snd_pcm_uframes_t alsa_period_size;
err = snd_pcm_hw_params_get_period_size(hwparams, &alsa_period_size,
nullptr);
if (err < 0)
throw FormatRuntimeError("snd_pcm_hw_params_get_period_size() failed: %s",
snd_strerror(-err));
AlsaSetupSw(pcm, alsa_buffer_size - alsa_period_size,
alsa_period_size);
FormatDebug(alsa_output_domain, "format=%s (%s)",
snd_pcm_format_name(hw_result.format),
snd_pcm_format_description(hw_result.format));
FormatDebug(alsa_output_domain, "buffer_size=%u period_size=%u",
(unsigned)alsa_buffer_size, (unsigned)alsa_period_size);
(unsigned)hw_result.buffer_size,
(unsigned)hw_result.period_size);
AlsaSetupSw(pcm, hw_result.buffer_size - hw_result.period_size,
hw_result.period_size);
auto alsa_period_size = hw_result.period_size;
if (alsa_period_size == 0)
/* this works around a SIGFPE bug that occurred when
an ALSA driver indicated period_size==0; this
@ -435,7 +419,7 @@ AlsaOutput::Setup(AudioFormat &audio_format,
period_frames = alsa_period_size;
silence = new uint8_t[snd_pcm_frames_to_bytes(pcm, alsa_period_size)];
snd_pcm_format_set_silence(format, silence,
snd_pcm_format_set_silence(hw_result.format, silence,
alsa_period_size * audio_format.channels);
}